A 2.4-GHz 1.3-mW OQPSK RF Front-End TX Based on an Injection-Locked Power Amplifier

An injection locking power amplifier is presented. The proposed solution, tailored to quadrature phase shift keying (QPSK) modulation for IoT has been realized by exploiting the property of an injection-locked frequency divider to work as a phase rotator. Hence, the divider's output is directly coupled to the antenna by a transformer to deliver the desired output power. The combination of these two ideas resulted in a high-efficiency, high-bandwidth QPSK RF front-end for IoT, capable of operating at up to 120 Mbit/s and delivering 1.3-mW output power while burning 3.4 mW.